In the fabrication of semiconductor devices such as integrated circuits, memory cells, and the like, a series of manufacturing operations are performed to define features on semiconductor wafers (“wafers” or “substrates”). The wafers include integrated circuit devices in the form of multi-level structures defined on a silicon substrate. At a substrate level, transistor devices with diffusion regions are formed. In subsequent levels, interconnect metallization lines are patterned and electrically connected to the transistor devices to define a desired integrated circuit device. Also, patterned conductive layers are insulated from other conductive layers by dielectric materials.
The various wafer manufacturing operations require handling and movement of the wafer. For instance, some manufacturing operations require vertical movement of the wafer at a given location, and employ a lifting device to provide this vertical movement of the wafer. A basic wafer lifting device may be defined to simply move a wafer from one vertical level to another vertical level, without regard to potential interference or collision along the vertical path of travel. In some wafer manufacturing systems, there could be other moving components that may enter the vertical path of travel of the wafer lifting device, thereby creating a potential for interference or collision along the wafer lifting path. It should be appreciated that such an interference or collision could result in breakage of the wafer lifting device, the component involved in the collision, and/or the wafer itself, if present on the wafer lifting device or component at the time of the collision. As expected, such breakages can be extremely costly in terms of product loss and system downtime.